A relatively extensive survey of groundwater contaminants is performed in urban and industrial contexts, at the regional scale (Walloon Region of Belgium), outside spots of contamination related to ... [more ▼]

A relatively extensive survey of groundwater contaminants is performed in urban and industrial contexts, at the regional scale (Walloon Region of Belgium), outside spots of contamination related to contaminated sites. More specifically, the most detected inorganic trace elements and organic contaminants are identified and their levels of occurrence are described statistically. Mechanisms that can explain their occurrence in groundwater are discussed. From a more pragmatic point of view, the data set has been also used to derive upper limits of pollutant background concentrations to be used in decision-making related to the management of contaminated groundwater in urban and industrial environments. The results presented are based on 243 samples from 8 sectors located in different geological contexts and different urban and industrial contexts. Each groundwater sample was analyzed for 19 inorganic trace elements, 61 organic micro-pollutants and 10 major and minor elements. Five physico-chemical parameters were measured in the field, at the time of sampling to determine the environmental conditions prevailing in groundwater. For comparison, existing groundwater analyses in natural context, available for the entire Walloon Region, were compiled from several databases. Cumulative distribution function plots allow comparing the distributions of inorganic trace elements in urban and industrial sectors to those obtained at the scale of the entire Walloon region. Cumulative distribution function plots are also used to compare the distribution of the inorganic trace elements in the different lithologies, in urban and industrial contexts. The composition of groundwater is altered in urban and industrial sectors with increased concentrations for most inorganic trace elements and organic contaminants. Anthropogenic influence is not limited to inputs of pollutants but also to alterations of subsurface environmental conditions, in particular redox conditions, resulting in the mobilization of pollutants. The influence of lithology is also marked in the data set. [less ▲]

In the context of the Water Framework Directive (EP and CEU, 2000), management plans have to be set up to monitor and to maintain water quality in groundwater bodies in the EU. In heavily industrialized ... [more ▼]

In the context of the Water Framework Directive (EP and CEU, 2000), management plans have to be set up to monitor and to maintain water quality in groundwater bodies in the EU. In heavily industrialized and urbanized areas, the cumulative effect of multiple contaminant sources is likely and has to be evaluated. In order to propose adequate measures, the calculated risk should be based on criteria reflecting the risk of groundwater quality deterioration, in a cumulative manner and at the scale of the entire groundwater body. An integrated GIS- and flux-based risk assessment approach for groundwater bodies is described, with a regional scale indicator for evaluating the quality status of the groundwater body. It is based on the SEQ-ESO currently used in the Walloon Region of Belgium which defines, for different water uses and for a detailed list of groundwater contaminants, a set of threshold values reflecting the levels of water quality and degradation with respect to each contaminant. The methodology is illustrated with first results at a regional scale on a groundwater body-scale application to a contaminated alluvial aquifer which has been classified to be at risk of not reaching a good quality status by 2015. These first results show that contaminants resulting from old industrial activities in that area are likely to contribute significantly to the degradation of groundwater quality. However, further investigations are required on the evaluation of the actual polluting pressures before any definitive conclusion be established. [less ▲]

In the context of the Water Framework Directive, management plans have to be set up about water quality issues in surface and ground water bodies in the EU. In heavily industrialised and urbanised areas ... [more ▼]

In the context of the Water Framework Directive, management plans have to be set up about water quality issues in surface and ground water bodies in the EU. In heavily industrialised and urbanised areas, the cumulative effect of multiple contaminant sources is likely to present a risk which has to be evaluated. In order to propose adequate measures, the calculated risk should be based on criteria reflecting the risk of water quality deterioration, in a cumulative way and at the scale of the whole surface water or groundwater body. An integrated GIS- and flux-based risk assessment approach for groundwater and surface water bodies is described with a regional scale indicator for the evaluation of the quality status of the groundwater body. It is based on the SEQ-ESO currently used in the Walloon Region of Belgium which defines, for different water uses and for a detailed list of groundwater contaminants, a set of threshold values reflecting the levels of water quality and degradation with respect to each contaminant. The methodology is illustrated with a first real scale application on a groundwater body corresponding to a contaminated alluvial aquifer which has been classified at risk of not reaching a good quality status by 2015. [less ▲]

In the context of the water framework directive, management plans have to be set up about water quality in surface and groundwater bodies in the EU. One of the first steps is to evaluate the risk of ... [more ▼]

In the context of the water framework directive, management plans have to be set up about water quality in surface and groundwater bodies in the EU. One of the first steps is to evaluate the risk of contamination of these water resources, and particularly the risk posed by contaminated industrial sites. From the perspective of water resource management, each of these sites taken individually does not necessary constitute a major threat. However, in heavily industrialised and urbanised areas, the cumulative effect of multiple contaminant sources is likely to present a risk. In order to propose adequate but still economically reliable measures, the calculated risk should be based on a so-called megasite approaches using criteria reflecting the water quality deterioration, in a cumulative way, at the scale of the whole surface water or groundwater body. A GIS-based regional risk assessment approach is developed here for groundwater bodies using the SEQ-ESO currently used within the Walloon Region as indicator to reflect the quality status of the groundwater body. The approach is applied on the groundwater body RWM073 “Gravels and alluvial deposits of the Meuse river between Engis and Herstal”, identified at risk of not reaching a good quality status by 2015. The different steps of this methodology consist of an inventory of proved or potential contaminating industrial sites, a numerical modelling of pollutants behaviour at the scale of the groundwater body and the application of the SEQ-ESO that finally gives a global quality status of the whole groundwater body. This analysis also serves as basis for a socio-economic approach intending to provide indications on costs and benefits generated by total or partial remediation of the contaminated groundwater bodies according to the different management scenarios. [less ▲]